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how to know the zener working voltage through band colour

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Ju susantyo

New Member
i've been working on repairing some dc driver lenze brand, the igbt seems to be blown, also with the igbt blown, some diode maybe zener also blown, i've checked with other working unit and found that the zener only have 1 band, some of it has green band and some of it has black band, seems like this diode is a melf package L, i've come to some reading about this kind of zener and found out there r 2 types of this diode, bzv49 series 1 watt and bzv55 series 500 mw, both of which has a working voltage range of 2.4 to 75 volt .... how can we know the working voltage of this zener ? including the wattage, can we crosscheck this diode voltage with the igbt datasheet and maybe this zener is somekind of thing called freewheeling of antiparallel diode ?

also there r some smd zener with sot23 package with marking code w70 04 blown, can anybody also advise me what this w70 04 zener working voltage ?

igbt code is : BSM50GD120DN2_B10

driver is : lenze EVS9326-ES
 

DerStrom8

Super Moderator
Zeners most likely will not be used for a freewheel diode. Schottkys are generally used for that purpose.

You do not provide enough information on your zener diode to answer your other questions.
 

Ju susantyo

New Member
Thanks a lot for the answer derstrom8, i try with good diode from other working unit, feed it with 24v and 10k resistor, the voltage read around 8.2v, can we assume this is a 8.2v zener ? there are board with Black band, some with yellow band and the other with green band
 
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